Imaging devices, such as printers, often employ a print head for printing on a printable medium, such as paper. Ink is usually supplied to the print head from an ink reservoir or ink tank via a flow passage. The ink tank and print head may form a single print cartridge unit or may comprise separate components. During printing, ink flows from the ink tank to the print head through some conduit.
Ink tanks are vented to atmospheric pressure to prevent excessive vacuum pressures within the reservoir that can reduce or prevent ink flow to the print head. In addition, venting relieves pressure buildups that can occur when an ink tank is exposed to extreme environmental conditions, e.g., that can be encountered during shipping, such as high temperature in motor vehicles or low pressures in airplanes at high altitudes.
During packaging and shipping, an ink tank is shipped to the customer in a package that seals the air vent using some type of sealing component. This ensures that the pressure differentials during altitude change, etc do not affect the internal components or operability of the ink tank. Once the ink tank is removed from a package, the user is instructed to remove the sealing component from the vent. If an ink tank with its air vent sealed is installed into a printer and the printer starts to print, the backpressure within the print head increases. As a result, the heater and nozzles in the print head chip may be overwhelmed and the print head may become de-primed. Once de-primed, the print head may catastrophically fail, and thereby may require replacement.
As a result, there is a need for ink tanks having components designed to prevent a print head from using a sealed ink tank and thereby prevent catastrophic failure.